Drift Compensator for a Tuning Device

ABSTRACT

An apparatus coupled to, or integrated with, a tuner. This apparatus, which may be referred to herein as a “compensator,” may operate to adjust a frequency of the tuner to counteract drift or error that may cause the tuner to erroneously tune to an inaccurate or undesired frequency. The compensator may be implemented as hardware or software, and may be stand-alone or integrated into the tuner and/or LNBF.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Application No. 61/018,083, titled “Drift Compensator for aTuning Device,” filed on Dec. 31, 2007 and naming Edmund F. Petruzzellias inventor. This application also incorporates by reference the patentapplication filed on the same date as this document and titled “DriftCompensator for a Tuning Device,” identified as attorney docket no.189349/US/3 (ES-1099.2).

TECHNICAL FIELD

Embodiments generally relate to compensating for drift in a satellitesignal receiving system, and more particularly to compensate for anoffset drift generated by an oscillator of a tuning device.

BACKGROUND DISCUSSION

Many current satellite receiving systems employ a low noise blockconverter with a feed (“LNBF”) to tune a satellite dish in order toreceive broadcast signals at a set-top box. Oftentimes, a localoscillator circuit supplies a base tuning frequency for the LNBF anddish. The local oscillator may be, for example, a dielectric resonatoroscillator (“DRO”).

Over time, a DRO's base tuning frequency may drift due to age ortemperature. When drift occurs, the perceived frequency of any broadcastsatellite signal, as measured by a demodulator associated with a set-topbox in communication with the LNBF, no longer matches the actualfrequency of the broadcast. Accordingly, to the demodulator, dish andany attached equipment like a set-top box or digital video recorder, adesired transponder signal may appear to be lost when in fact thedemodulator is erroneously searching for it (or tuning to it) at thewrong frequency.

In addition, such drift may be difficult to diagnose because it may beintermittent. For example, certain DROs experience excessive drift onlywhen their operating temperature exceeds a threshold. Thus, the drift ofa DRO may be sufficiently large to remove a satellite signal from afrequency band searched by the system only if the ambient temperature isover the threshold. For example, if the temperature is sufficientlycool, the drift may be low enough that the satellite signal is withinthe searched frequency band and therefore acquired during normal systemoperation. This may lead to intermittent loss of a satellite signal onlyon particularly hot days or afternoons, for example. It should be notedthat drift may be exaggerated by either heat or cold. The transientnature of such signal loss may make it difficult to diagnose and fixsuch a channel loss.

SUMMARY

One embodiment generally may be an apparatus coupled to, or integratedwith, a tuner. This apparatus may operate to adjust a frequency of thetuner to counteract drift or error that may cause the tuner toerroneously tune to an inaccurate or undesired frequency. Thecompensator may be implemented as hardware or software, and may bestand-alone or integrated into the tuner and/or LNBF.

Another embodiment takes the form of a method for compensating for driftin a satellite tuning device, including the operations of: receiving arequest to tune to a channel carried on a transponder signal;determining an offset value for the transponder signal; adding theoffset value to a center frequency; searching a frequency band aroundthe center frequency; locating the transponder signal within thefrequency band at a perceived frequency; setting the offset value toequal the difference between a standard frequency for the transpondersignal and the perceived frequency; and storing the offset value in anentry.

The embodiment may employ an offset value that is initially zero.

The embodiment may further store a temperature with the offset value.

The embodiment may also store the offset value on a per-channel basis.Further, the offset value may be copied to at least one other entry, theat least one other entry associated with a second channel carried on thesame transponder signal, satellite and/or polarity band.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 generally depicts an exemplary operating environment for oneembodiment.

FIG. 2 is a flowchart depicting the general operation of an exemplaryembodiment.

FIG. 3 generally depicts a hardware configuration of an embodiment.

DETAILED DESCRIPTION

One embodiment takes the form of an apparatus coupled to, or integratedwith, a tuner. This apparatus, which may be referred to herein as a“compensator,” may operate to adjust a frequency of the tuner tocounteract drift or error that may cause the tuner to erroneously tuneto an inaccurate or undesired frequency. The compensator may beimplemented as hardware or software, and may be stand-alone orintegrated into the tuner and/or LNBF.

As one illustrative and non-limiting example, a low noise blockconverter with a feed is often coupled to a satellite dish to receivesignals broadcast by a satellite. The LNBF may include a dielectricresonator oscillator, which is tuned to a particular local oscillator(LO) frequency that serves as a frequency reference for the LNBF. ThisLO frequency may be used by the LNBF as a baseline for tuning to one ormore particular frequencies in order to receive the broadcast signal(s).That is, the tuner may search a band of frequencies centered on achannel frequency down-converted using the LO frequency, in order tofind and lock onto the satellite signal. The frequency of a givenbroadcast signal is generally either up- or down-converted from anexpected satellite signal by the LNBF. In some cases, a low-noise blockconverter (“LNB”), without a feedhorn, may be used. Accordingly,references to an LNBF herein should be understood to encompass an LNBand vice versa.

However, the DRO's LO frequency may shift over time due to aging of theDRO or exposure to adverse environmental conditions, such as heat. Sincethe frequency band searched by the tuner is centered on the transmittedchannel frequency, a sufficiently large drift in the LO frequency maycause the searched frequency band to be outside the frequency of thesatellite receiver tuner. In such a case, the tuner is unable to acquirethe satellite signal and considers that signal to be lost or inactive.

The present embodiment may account for drift or shift in the DRO's LOfrequency by adjusting the frequency channel used by the tuner (or othertuning device). The embodiment may, for example, determine whether thesatellite broadcast signal's frequency was last obtained above or belowthe reference channel frequency and shift the searched frequency bandaccordingly. For example, if the satellite broadcast signal was lastregistered two megahertz (MHz) below the default LO frequency, theembodiment may decrease the tuner frequency by two MHz, effectivelymaking the new LO frequency equal the last registered broadcast signalfrequency.

Alternatively, the embodiment may adjust the tuner frequency upward ordownward by a fixed interval if the satellite broadcast frequency cannotbe found within the frequency band searched by the tuner. The directionin which the embodiment adjusts the LO frequency is generally dependenton the value of the last received broadcast signal frequency.

It should be noted that the satellite broadcast frequency does notchange, although the broadcast frequency as perceived by the tuningdevice varies. This occurs because most standard tuning devices presumethe LO frequency of the DRO remains constant; such tuning deviceseffectively cannot detect the DRO's frequency drift. Thus, although tothe tuning device the satellite broadcast frequency may appear tochange, the broadcast frequency remains constant and such changesreflect only the amount of drift in the DRO's LO frequency. Accordingly,reference is made herein to both a “perceived frequency” and “standardfrequency.” The perceived frequency is the frequency, as measured by thetuner, at which the tuner detects a desired or selected channel. Theperceived frequency for a channel will vary with the drift of the DRO.By contrast, the standard frequency is the frequency at which a desiredor selected channel is broadcast as measured from unbiased, non-driftingequipment by the receiver's tuner.

In other words, the perceived frequency may be thought of as a localmeasurement by a tuner of the selected frequency and incorporates thebias/drift of the DRO. The perceived frequency is always statedthroughout this document with reference to DRO and thus is relative tothe tuning capabilities of the tuner; the perceived frequency isgenerally offset from the selected frequency by the drift of the DRO.The standard frequency is always stated throughout this document withreference to an absolute, non-biased measurement. Accordingly, giventhat a signal's transmission frequency generally is invariant over time,its standard frequency is likewise invariant (and equal to thetransmission frequency) but its perceived frequency may change due tovariables in operation such as the passage of time or environmentalvariables.

FIG. 1 depicts an exemplary operating environment for an embodiment. Thefollowing is intended only as a high-level overview of the environmentand should not be considered a limiting technical description.

In one exemplary environment, a satellite 100 broadcasts communicationssignals to a satellite dish 105. Each signal is sent from a differenttransponder at a different frequency. A single transponder signaltypically contains data for multiple channels. That is, data for eachchannel is modulated onto the transponder signal in manners known tothose of ordinary skill in the art. Accordingly, if the tuner connectedto the satellite dish 105 is tuned to receive a single transpondersignal, it may receive (via the satellite dish) multiple channels onthat transponder signal. These multiple channels (e.g., the transpondersignal) may be downconverted en masse by the LNBF 110. Accordingly, theterms “transponder signal” and “channel signal” are used interchangeablyherein.

The satellite dish 105 may be tuned to a variety of frequencies via aLNBF 110. An oscillator 115, such as the aforementioned DRO, may be usedby the LNBF 110 to downconvert the incoming signal from the satellitedish 105. Generally, the satellite dish may receive signals from thesatellite only if it is tuned to the signal's frequency via the LNBF110. The oscillator 115 provides a base frequency from which the LNBF110 may downconvert the incoming signal.

If the base frequency of the oscillator 115 is off from its anticipatedor expected value, then the oscillator has “drifted” from its frequency.Such drift is generally only detectable through empirical use of theoscillator, LNBF 110 and set-top box 125. That is, if the tuner 140tunes the set-top box 125 to a transponder frequency but the dish cannotobtain the transponder signal, one possible cause is that the oscillator115 has drifted off its initial or expected base frequency. If theoscillator frequency drifts in this manner, the frequency to which thesatellite receiver 125 is tuned by the tuner 140 is off by the amount orvalue of the drift. Such drift may occur due to age of the oscillator,variances in ambient temperature (especially heat), or otherenvironmental conditions.

The LNBF 110 may transmit received signals (typically across a coaxialcable) to a set top box (“STB”) 125. In particular, the signal may bereceived by a demodulator 130 in the STB. The demodulator 130demodulates from the transponder signal the data for a channel selectedvia the STB. The demodulator 130 then broadly reconstructs theindividual channel from the channel data on the transponder signal andtransmits it to a display device 135 for display. Further, a user of theSTB may manipulate the tuning of the tuner 140 by changing channels orselecting a new channel via the STB. In such operation, the STB signalsto the tuner 140 that the user has requested the embodiment tune toanother channel. The tuner 140 then retunes to detect an incoming signalon the corresponding transponder signal.

FIG. 2 is a flowchart depicting the general operation of an exemplaryembodiment. The operations are initiated when the tuner is instructed totune to the broadcast frequency or otherwise look for the broadcastsignal. This may occur, for example, when a user changes channels via aSTB. The STB then instructs the tuner to acquire a satellite broadcastsignal corresponding to the new channel. In order to do so, the tunermay need to tune to a new frequency. (This can occur, for example, whenthe new channel is broadcast by a different satellite than the previouschannel or on a different frequency by the same satellite.)

Generally, the flowchart depicts the operations executed to determine afrequency of a transponder signal, display the content of the signal andstore the signal frequency for later use. It should be noted thatcertain operations set forth in the following description and on FIG. 2may be omitted or performed in an order other than that shown.Particular, non-limiting examples of such changes to the operations ofFIG. 2 are provided after the discussion of the flowchart.

The method begins in operation 200, wherein the embodiment is activated.This may occur, for example, when a STB is turned on or a command totune to particular channel or frequency is received by the STB. Once theembodiment is active, it selects a particular transponder in operation200. The selected transponder generally includes or transmits the signalcorresponding to the desired channel or frequency, as generallyindicated in operation 205. As discussed above, the local oscillatoroperates to translate the transponder frequency. As also discussedabove, a demodulator retrieves or breaks out the information for thegroup of signals from the carrier wave of the transponder.

In operation 210, the embodiment determines if an offset has beenpreviously calculated and stored. An offset is used to shift theperceived standard frequency of the selected channel. For example, if achannel is typically broadcast at 1200 MHz then 1200 MHz is the“standard frequency” for the channel. However, if the local oscillatorhas drifted due to age, temperature or environment, the perceivedfrequency of that channel may be 1205 MHz. In such a case, the offsetwould be 5 MHz, which is the difference between the perceived channelfrequency and the standard frequency.

If no offset has been previously stored, the embodiment executesoperation 215 and uses the standard frequency as a center frequency. Theuser of the center frequency is described in more detail below withrespect to operation 230. Following operation 215, the embodimentaccesses operation 225.

However, if an offset was previously stored, the embodiment executesoperation 220 after operation 210. In operation 220, the embodiment setsthe center frequency to equal the desired or selected channel's standardfrequency plus the offset value. Thus, to continue the example above,the embodiment would set the center frequency to equal 1205 MHz (e.g.,the 1200 MHz standard frequency for the selected channel plus thepreviously determined 5 MHz offset). The set-top box tuner is tuned tothe center frequency determined in operation 220. Accordingly, theoffset may at least partially compensate for drift of the localoscillator. Although the local oscillator still drives the LNBF outputto an incorrect frequency, the addition of the offset compensates forthe drift and sets the tuner to the proper frequency. It should be notedthat the offset may be negative, in which case the perceived frequencywould be lower than the standard frequency of the channel.

Next, the embodiment determines an initial deviation in operation 225.Typically, the initial deviation is a fixed value. For example, in oneembodiment the initial deviation is plus or minus 5 MHz. Although thedeviation is shown as being set to +/−5 MHz in operation 225 of FIG. 2,it should be understood that this is an exemplary value used by oneexemplary embodiment. Accordingly, the deviation may be set to differentvalues in alternative embodiments.

Once the deviation is set, the embodiment executes operation 230. Inoperation 230, the embodiment searches a frequency range for the signalcarrying the desired channel (e.g., the desired signal). The frequencyrange searched by the embodiment generally ranges from one deviationless than the center frequency to one deviation greater than the centerfrequency. So, continuing the example, if the center frequency is 1205MHz (representing a standard frequency of 1200 MHz and an offset of 5MHz) and the deviation is 5 MHz, the range in which the embodimentinitially searches for the desired signal is 1200 MHz to 1210 MHz. Itshould be noted that the signal or channel frequency is also thedown-converted transponder frequency.

Typically, although not necessarily, the embodiment will begin searchingat the center frequency and increment up and down the frequency rangeuntil the minimum and maximum frequencies are reached. Alternativeembodiments may employ other search methodologies. For example, someembodiments may search from the minimum frequency of the frequency rangeto the maximum frequency of the range, while other embodiments mayreverse this process. As still another example the frequency range maynot be centered on the center frequency; the frequency range may beskewed to on side of the center frequency or the center frequency mayeven define a boundary of the frequency range. Accordingly, embodimentsmay employ any search methodology to search within the frequency range.

In operation 235, the embodiment determines if the signal has beenlocated within the frequency range. Generally, once the signal islocated, the embodiment ceases searching the remainder of the frequencyrange.

In the event the signal is found, the demodulator 130 (shown in FIG. 1)may demodulate the carrier signal and reconstruct the channel data asdescribed above. The data in the desired or selected channel signal(e.g., video, audio, metadata and so forth) may be transmitted from theset top box 125 and demodulator 130 in particular to the display 135 fordisplay as part of operation 240. The display may depict the data asanother part of this operation.

In operation 245, a new offset for the selected signal is determined.The offset is set to equal the difference between the perceived signalfrequency (e.g., the perceived frequency at which the signal was foundin operation 235) less the standard frequency for the selected channel.In other words, the offset for any given signal is set in operation 245to equal the drift experienced by the DRO.

Once the offset is determined and assigned, it is stored in operation250. The offset may be stored in a table or database. Each channel oneach satellite may have a unique offset entry in the table/database, sothat a tuning table containing offsets for each channel may be created.In this manner, as the embodiment is tuned to multiple transponderfrequencies or multiple channels are selected by a user, the embodimentmay record offsets for each such channel. Later tuning to each suchchannel may thus occur more quickly and efficiently by employing theoffset; the embodiment may use the offset in operation 220, above, toset the center frequency equal to the last known perceived frequency forthe requested channel.

It should be noted that the offset may be common to a number ofchannels, insofar as multiple channels are carried on a singletransponder signal. Thus, to the extent a second channel is known to bemodulated on the same transponder frequency as the current selectedchannel, the offset entry for the current selected channel may be copiedinto the offset entry for the second channel. Alternatively, the tuningtable may have entries corresponding only to transponders instead ofindividual channels.

After the offset is stored, the embodiment terminates the method inoperation 275.

Returning briefly to operation 235, if no signal is found within thefrequency range then operation 255 is accessed. In operation 255, theembodiment increments the size of the deviation. The increment size mayvary arbitrarily between embodiments. For example, in one embodiment theincrement may be 1 MHz and in another embodiment it may be 2.5 MHz.Incrementing the deviation permits the embodiment to search a largerfrequency range in its attempt to acquire the transponder signal.

Certain embodiments may not increment the size of the deviation inoperation 255, but instead maintain the same size deviation andincrement the center frequency instead. Thus, the embodiment may searcha band of frequencies of a constant size (for example, +/−5 MHz aroundthe center frequency), but the upper and lower limits of this band maychange with each execution of operation 255.

Following operation 255, the embodiment increments a count variable inoperation 260. The count variable tracks the number of times theembodiment has unsuccessfully searched a frequency range and/or thenumber of times the deviation has been increased/incremented. Next, inoperation 265, the embodiment determines if the count exceeds athreshold. If so, then the embodiment executes operation 270 and reportsor acknowledges that it cannot locate the transponder signal. Forexample, the embodiment may cause the display 130 to show a “No Signal”message or may report to a transmission or troubleshooting facility thatthe signal cannot be located. After operation 270, the method ends inend state 275.

Instead of incrementing and checking a count variable, an embodiment mayinstead directly employ an incremented frequency in operations 260 and265. For example, in an embodiment incrementing a center frequencyinstead of expanding the size of a deviation, the center frequency (oran upper/lower limit of the frequency band) may be checked to see if ithas reached a threshold in operation 265. Further, it should beunderstood that the threshold may be arbitrarily set to any valuedesired, subject only to the limits of any hardware configured toexecute the operations.

If, however, the count does not exceed the threshold in operation 265,the embodiment again executes operation 230 and searches within onedeviation on either side of the center frequency. It should be notedthat the deviation has been increased in operation 255 and according thesize of the searched frequency range likewise increases. In certainembodiments, the embodiment may only search those portions of thefrequency range that have not been previously searched in an iterationof operation 230. That is, the embodiment may only search in a band thesize of the deviation increment at the top and bottom of the newfrequency range.

It should also be noted that certain embodiments may omit operations260-270 and simply search until the desired transponder signal islocated. Yet other embodiments may omit operations 260 and 265, insteaddetermining if the deviation exceeds a maximum and proceeding tooperation 270 if this occurs.

Additionally, it should be noted that certain operations discussed withrespect to FIG. 2 may be performed in different orders. For example,operations 245 and 250 may occur before operation 240. Likewise,operations 260 and 265 ma occur before operation 255. Accordingly, themethod shown on FIG. 2 and the order of operations therein is intendedto be exemplary rather than limiting.

The aforementioned tuner table and the various offset values may bestored in memory or a storage device associated with, collocated with,or contained within the set top box 120. Typically, although notnecessarily, the tuner table and methodology described herein isimplemented as software accessible by a processor of the set top box. Incertain embodiments, the tuner table and methodology may be implementedin firmware, software or hardware. The firmware, hardware, and/orsoftware may reside in any of the set-top box, the LNBF, and/or any oftheir constituent elements. Similarly, portions of such firmware,hardware, and/or software may be distributed between the set-top box,LNBF, and/or constituent elements.

In addition to storing one or more offset values in the tuner table,alternative embodiments may store additional information in each entryof the tuner table. For example, an entry for a specific channel ortransponder may include not only an offset but also a temperaturemeasured when the offset was determined. Additional entries for eachchannel or transponder may be generated when the offset changes or whenthe temperature changes. Since the drift of the DRO 115 may vary withtemperature, certain embodiments may look up all entries correspondingto a selected channel or transponder and employ the offset having atemperature value most closely matching a current temperature to moreprecisely tune the demodulator against an expected DRO drift. Suchembodiments may include a thermometer or other device for measuringtemperature electronically associated with the embodiment. Likewise,alternative embodiments may record the time at which each offset ismeasured.

Still other embodiments may automatically report to a troubleshootingfacility every time an offset is generated and stored, or whenever anoffset exceeds a threshold. Such automatic reporting may facilitatedispatching of and/or repair by a technician. In this manner, a driftingDRO 115 may be diagnosed and repaired even before a customer or user ofthe embodiment is aware of any drift. The embodiment may likewise makethe various stored offset data available to a technician for diagnosisand repair of any issues with the embodiment. As an example, certainembodiments may store not only offsets for all channels or transponders,but also the highest offset ever recorded for any channel ortransponder. This latter data may be useful to a technician attemptingto repair the embodiment or compensate for drift during operation inexcessive temperatures or other unfavorable environments.

As yet another alternative, the embodiment may display a message on thedisplay 130 instructing the user to call a repair center ortroubleshooting facility and report the drift when an offset isgenerated.

FIG. 3 depicts an embodiment showing sample hardware that may be used tocompensate for a drift in a local oscillator. Generally, a set-top box300 (or other television receiver) may include a tuner 310, demodulator315 and microprocessor 320. The set-top box 300 may be in communicationwith a LNBF or LNB 305 (for simplicity's sake, referred to herein as an“LNBF”). The LNBF 305 may include a LNBF microprocessor 325, a DRO 330and a varactor diode 335.

During operation, the tuner 310 transmits commands to the LNBFmicroprocessor 325 via a communication protocol, such as DiSEqC oranother appropriate protocol. Generally, these commands instruct theLNBF microprocessor 325 to return the DRO 330 to a nominal centerfrequency, which is based on a standard frequency plus a frequencyoffset, as generally described above. The frequency offset may beobtained by any means described herein or known to those skilled in theart. The tuner 300 may communicate with the LNBF 305 via, for example, acoaxial cable, other wired connection, or wireless connection such asBLUETOOTH, infrared frequencies, radio frequencies, wireless homenetworks and so forth.

For example, the frequency offset may be determined by the demodulator315 as the signal is detected. The demodulator 315 may determine avoltage to be applied to the varactor diode 335 by the LNBFmicroprocessor 325. This voltage is generally proportional to theoffset. That is, if the offset is 110% of the standard frequency, thevoltage applied to the varactor at the intermediate node 340 (e.g., thenode between the varactor diode and the DRO 330) is sufficient to tunethe DRO to 110% of the standard frequency by means discussed below.Among other operations, the set-top box microprocessor 300 may controlthe operation of the tuner 310 and demodulator 315, includingcommunications between such elements and the LNBF 305.

The varactor diode 335 has a capacitance that varies with the voltageapplied to the varactor. Thus, as voltage is increased at theintermediate node 340, the capacitance of the varactor diode alsochanges. Generally, the capacitance of the varactor is inverselyproportional to the square root of the applied voltage at theintermediate node. Thus, as the intermediate node's voltage increases,the varactor diode's capacitance decreases. This, in turn, effectivelychanges the electromagnetic fields coupling the tuning stub 345 to theDRO 330, thereby changing the DRO's frequency. That is, the varactordiode 335 capacitively loads the tuning stub 345, which makes theelectrical field of the tuning stub appear longer and thereby changesthe electrical coupling to the DRO. This retunes the LO frequency of theDRO to match the prior LO frequency plus the frequency offset.

Certain embodiments may take a dual hardware/software approach tolocating a transponder signal as discussed herein. For example, anembodiment may initially employ hardware, such as that discussed withrespect to FIG. 3, to search for a transponder signal. When the tuninglimits of the varactor diode are reached, the embodiment may employsoftware to continue searching. IN such an embodiment, the centerfrequency used initially by the software may fall within the final bandof frequencies searched by the hardware or may be equal to the centerfrequency last searched by the hardware plus one deviation.

The foregoing has been generally described with respect to a set-topbox. However, it should be appreciated that the various embodiments maybe implemented in or with other television receivers, such as a cablebox, digital video recorder or other suitable technology. Accordingly,although this description specifically discusses set-top boxes, it isintended to generally encompass these other television receivers, aswell.

It should be appreciated that the method and operations describedherein, may be executed by appropriately configured hardware, such as anintegrated circuit or one or more electronic components, or by aprocessor or other computing device/system configured to executesoftware that performs the aforementioned method and/or operations. Forexample, a dedicated circuit may be implemented in a set-top box toprovide the functionality disclosed herein.

In conclusion, various embodiments have been described with respect toparticular apparatuses and methods. It will be appreciated by those ofordinary skill in the art that the hardware, software, apparatuses andmethods described herein may be modified and changed without departingfrom the spirit and scope of the embodiments disclosed herein. Forexample, a different type of oscillator other than a DRO may experiencedrift and thus may be corrected by a properly-implemented embodiment. Asyet another example, an embodiment may be employed in a system receivinga terrestrial transmission or transmission other than from a satelliteor at a frequency not typically used to transmit satellite programming.As still another example, an embodiment may be incorporated into astereo receiver, media center, computing device, digital versatile diskplayer, television, monitor, or any other type of audiovisual orelectronic equipment other than a set top box. As still another example,an embodiment may be a stand-alone device plugged into a STB or otherequipment. Accordingly, the proper scope of the invention is defined bythe following claims.

1-20. (canceled)
 21. An apparatus for compensating for drift in asatellite tuning device, comprising: a tuner configured to tune to achannel carried on a transponder signal; a compensator associated withthe tuner, the compensator configured to: determine an offset value forthe transponder signal; add the offset value to a center frequency;searching a frequency band around the center frequency within adeviation of a first size; the compensator further configured to executethe following actions in the event that the transponder signal islocated within the frequency band at a perceived frequency: set theoffset value to equal the difference between a standard frequency forthe transponder signal and the perceived frequency; and store the offsetvalue in an entry; and the compensator further configured to execute thefollowing actions in the event that the transponder signal is notlocated within the frequency band at the perceived frequency: incrementthe size of the deviation such that the deviation is a of second size;search the frequency band around the center frequency within a deviationof the second size; locate the transponder signal within the frequencyband at the perceived frequency; set the offset value to equal thedifference between a standard frequency for the transponder signal andthe perceived frequency; and store the offset value in an entry.
 22. Theapparatus of claim 21, wherein the offset value is initially zero. 23.The apparatus of claim 22, wherein a temperature is stored with theoffset value.
 24. The apparatus of claim 22, wherein: the offset valueis stored on a per-channel basis; and the offset value is copied to atleast one other entry, the at least one other entry associated with asecond channel carried on the same transponder signal.
 25. The apparatusof claim 21, wherein the frequency band is centered on the centerfrequency.
 26. The apparatus of claim 21, wherein the frequency bandasymmetrically encompasses the center frequency.
 27. The apparatus ofclaim 21, wherein the center frequency defines a boundary of thefrequency band.
 28. A apparatus for compensating for drift in asatellite tuning device, comprising: a tuner configured to tune to achannel carried on a transponder signal; a compensator associated withthe tuner, the compensator configured to: search in a frequency bandcentered on a center frequency for a signal; in the event the signal isnot located, increment the center frequency by a deviation value toyield an adjusted center frequency; search a second frequency bandaround the adjusted center frequency for the signal; locate the signalwithin the adjusted center frequency; set the deviation value to equalthe difference between a standard frequency for the signal and afrequency at which the signal was located; and store the deviationvalue.
 29. The apparatus of claim 28, wherein in the operation ofincrementing the center frequency by a deviation value the compensatorapplies a voltage to a variable capacitor, to thereby adjust a frequencyof an oscillator resonating at the center frequency.
 30. The apparatusof claim 29, further comprising: a demodulator; wherein the compensatoris further configured to receive, from the demodulator, the standardfrequency for the signal, and to set the center frequency of thefrequency band to the standard frequency for the signal.
 31. Theapparatus of claim 28, wherein in the operation of incrementing thecenter frequency by a deviation value the compensator is furtherconfigured to adjust a software value for the center frequency.
 32. Theapparatus of claim 28, wherein the deviation value is stored on aper-channel, per-satellite basis.